Umbrella stand



FIG. 1 is a front perspective view of an umbrella stand showing the new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a left side elevation view thereof;

FIG. 5 is a right side elevation view thereof;

FIG. 6 is a front elevation view thereof; and,

FIG. 7 is a rear elevation view thereof.

The broken lines depict environment and portions of the article that form no part of the claimed design. 

CLAIM The ornamental design for an umbrella stand, as shown and described. 